1 files changed, 31 insertions, 24 deletions

diff --git a/src/mango/src/mango_idx.erl b/src/mango/src/mango_idx.erl
index c5f870d5b..4dd2e180d 100644
--- a/src/mango/src/mango_idx.erl
+++ b/src/mango/src/mango_idx.erl
@@ -20,7 +20,6 @@
 -export([
     list/1,
     recover/1,
-    for_sort/2,
 
     new/2,
     validate_new/2,
@@ -36,7 +35,7 @@
     def/1,
     opts/1,
     columns/1,
-    is_usable/2,
+    is_usable/3,
     start_key/2,
     end_key/2,
     cursor_mod/1,
@@ -57,9 +56,8 @@ list(Db) ->
     {ok, Indexes} = ddoc_cache:open(db_to_name(Db), ?MODULE),
     Indexes.
 
-get_usable_indexes(Db, Selector0, Opts) ->
-    Selector = mango_selector:normalize(Selector0),
 
+get_usable_indexes(Db, Selector, Opts) ->
     ExistingIndexes = mango_idx:list(Db),
     if ExistingIndexes /= [] -> ok; true ->
         ?MANGO_ERROR({no_usable_index, no_indexes_defined})
@@ -70,13 +68,17 @@ get_usable_indexes(Db, Selector0, Opts) ->
         ?MANGO_ERROR({no_usable_index, no_index_matching_name})
     end,
 
-    SortIndexes = mango_idx:for_sort(FilteredIndexes, Opts),
-    if SortIndexes /= [] -> ok; true ->
-        ?MANGO_ERROR({no_usable_index, missing_sort_index})
-    end,
+    SortFields = get_sort_fields(Opts),
+    UsableFilter = fun(I) -> is_usable(I, Selector, SortFields) end,
+    UsableIndexes0 = lists:filter(UsableFilter, FilteredIndexes),
+
+    case maybe_filter_by_sort_fields(UsableIndexes0, SortFields) of
+        {ok, SortIndexes} -> 
+            SortIndexes;
+        {error, no_usable_index} -> 
+            ?MANGO_ERROR({no_usable_index, missing_sort_index})
+    end.
 
-    UsableFilter = fun(I) -> mango_idx:is_usable(I, Selector) end,
-    lists:filter(UsableFilter, SortIndexes).
 
 recover(Db) ->
     {ok, DDocs0} = mango_util:open_ddocs(Db),
@@ -93,33 +95,38 @@ recover(Db) ->
     end, DDocs)}.
 
 
-for_sort(Indexes, Opts) ->
-    % If a sort was specified we have to find an index that
-    % can satisfy the request.
+get_sort_fields(Opts) ->
     case lists:keyfind(sort, 1, Opts) of
-        {sort, {SProps}} when is_list(SProps) ->
-            for_sort_int(Indexes, {SProps});
+        {sort, Sort} ->
+            mango_sort:fields(Sort);
         _ ->
-            Indexes
+            []
     end.
 
 
-for_sort_int(Indexes, Sort) ->
-    Fields = mango_sort:fields(Sort),
+maybe_filter_by_sort_fields(Indexes, []) ->
+    {ok, Indexes};
+
+maybe_filter_by_sort_fields(Indexes, SortFields) ->
     FilterFun = fun(Idx) ->
         Cols = mango_idx:columns(Idx),
         case {mango_idx:type(Idx), Cols} of
             {_, all_fields} ->
                 true;
             {<<"text">>, _} ->
-                sets:is_subset(sets:from_list(Fields), sets:from_list(Cols));
+                sets:is_subset(sets:from_list(SortFields), sets:from_list(Cols));
             {<<"json">>, _} ->
-                lists:prefix(Fields, Cols);
+                lists:prefix(SortFields, Cols);
             {<<"special">>, _} ->
-                lists:prefix(Fields, Cols)
+                lists:prefix(SortFields, Cols)
         end
     end,
-    lists:filter(FilterFun, Indexes).
+    case lists:filter(FilterFun, Indexes) of
+        [] ->
+            {error, no_usable_index};
+        FilteredIndexes ->
+            {ok, FilteredIndexes}
+    end.
 
 
 new(Db, Opts) ->
@@ -250,9 +257,9 @@ columns(#idx{}=Idx) ->
     Mod:columns(Idx).
 
 
-is_usable(#idx{}=Idx, Selector) ->
+is_usable(#idx{}=Idx, Selector, SortFields) ->
     Mod = idx_mod(Idx),
-    Mod:is_usable(Idx, Selector).
+    Mod:is_usable(Idx, Selector, SortFields).
 
 
 start_key(#idx{}=Idx, Ranges) ->